Emergence of a Multiple Input Multiple Output (Multiple Input Multiple Output, MIMO) technology brings a revolutionary change to wireless communication. In the MIMO technology, a plurality of antennas are deployed on a transmit end device and a receive end device, performance of a wireless communications system can be significantly improved. For example, in a diversity scenario, the MIMO technology can effectively improve transmission reliability. In a multiplexing scenario, the MIMO technology can greatly increase a transmission throughput.
In a MIMO system, a precoding technology is usually used to improve a channel, so as to improve a spatial multiplexing (Spatial Multiplexing) effect. Specifically, in the precoding technology, a precoding matrix that matches a channel is used to process a data stream obtained after spatial multiplexing (referred to as a spatial stream for short below), so as to precode the channel and improve received quality of the spatial stream.
Each spatial stream obtained after spatial multiplexing is corresponding to a column vector of a precoding matrix. In a precoding process, a transmit end device precodes the spatial stream by using the column vector. Therefore, the column vector may also be referred to as a precoding vector. The precoding vector may be determined by a receive end device and fed back to the transmit end device. According to the prior art, information indicating each precoding vector needs to be fed back for the precoding vector, so that when there are a relatively large quantity of spatial streams obtained after spatial multiplexing, high feedback overheads are generated by indicating these precoding vectors.